Agarwal, M. L.Prasad, Uday Kumar2016-09-152016-09-152012http://krishikosh.egranth.ac.in/handle/1/76821Two ecological homologue fruit fly species, viz. Bactrocera cucurbitae (Coquillett) and B. tau (Walker) (Diptera: Tephritidae: Dacinae: Dacini) are most pernicious pests of most cucurbits in India and many other countries. Studies/ experiments were carried out on their comparative morphology, biology, population dynamics and effect of weather components on the same, and control strategies by using different combination of baits, attractant and insecticide. Notes are given on the nomenclatural status and distribution of these Bactrocera species. Comparative morphological descriptions and illustrations have been given for immature stages, viz. eggs, three larval instars and pupae of these two Bactrocera species. Length and width of eggs of these species were 1.20-1.38 and 0.25-0.30 mm and 1.3-1.6 and 0.22-0.24 mm, respectively. In egg of B. cucurbitae anterior area behind micropyle was mammilate. Larval instars of these species had differences in the structures of their cephalopharyngeal skeletons, spiracles and caudal segments. Mouthhooks of third instar larvae of B. cucurbitae have small preapical teeth and the same was absent in B. tau. Numbers of tubules on outer margin of anterior spiracles were 17-20 and 14-16 in B. cucurbitae, and B. tau, respectively. These species had 7-14, and 14-18 spiracular hairs in dorsal and ventral bundles while their numbers were 4-7, and 5-9 in lateral bundles. Mature larva of B. cucurbitae had a dark line on intermediate area of caudal segment which was absent in B. tau. The pupa of B. cucurbitae had a dark line across the middle of posterior end. Adults of both species had three pairs of frontal setae. Gena is also yellowish in B. cucurbitae while in B. tau it has a dark spot below compound eye. Scutum is mostly rufous in B. cucurbitae and orange-brown in B. tau and three postsutural yellow vittae were present in both species. B. tau scutum has conspicuous black markings in areas between lateral and median postsutural vittae and also in areas behind humeral calli. Costal bands were continuous in both species. Wing of B. cucurbitae had a small spot on crossvein r-m and a large spot around crossvein DM-Cu while these spots are absent in B. tau. Abdominal tergites of both species had characteristic black markings. Characters of male genitalia and female ovipositors of these species have also been discussed and illustrated. Host range and nature of infestation and damage done by both species is discussed. Life history traits of both species include brief notes on adult feeding, mating, oviposition and larval activity. The preoviposition periods in B. cucurbitae and B. tau were 14-17 and 11-13 days, respectively while the number of eggs laid/ day by the female fly of these species varied between 8-15 and 6-12, respectively. Average incubation period; average larval duration; average pupal duration and total duration (egg to adult emergence) in B. cucurbitae and B. tau were 1.14, 1.24 days; 6.91, 7.10 days; 9.00, 10.40 days and 17.05, 18.74 days, respectively. The egg hatchability of B. cucurbitae and B. tau was 87.50 and 77.50 per cent, respectively. Average survival of their larvae and pupae were 82.50, 80.00; and 81.25, 75.00 per cent, respectively. Sex ratio (male: female) of these species were 1:1.36 and 1:1.27, respectively. Population dynamics of these Bactrocera species was studied at three locations during the years 2010-11 and 2011-12 by weekly count of male flies trapped in plastic bottle traps containing protein hydrolysate (as bait), cue-lure and spinosad. Adults of both species were available throughout during both years and exhibited somewhat uniform pattern in terms of their numbers during different months. Maximum mean weekly population of both species was observed in the months of August during both years of experimentation at all three locations and thereafter a decreasing trend was observed. The population of both species was either nil or negligible in the months of December and January and subsequently an increasing trend was observed in the populations of these two species. Besides this, the population of B. cucurbitae was much higher than B. tau. At all three locations maximum and minimum temperatures, minimum relative humidity at 14 hrs and rainfall showed a positive and significant correlation with populations of both species during both years while morning relative humidity at 7 hrs exhibited a negative correlation in all cases. Efficacy of different combinations of baits, attractant and insecticide was evaluated for annihilation of males of two Bactrocera species. These formulations were used in traps and had differences only in bait component. Maximum numbers of males of both species were annihilated in August followed by July. From September a decline was observed in the number of annihilated flies which reached at lowest level or nil in the months of December and January. Subsequently the rate of annihilation increased gradually with an increase in temperature. The formulation consisting of 5g Protein bait + Cue-lure (1ml) + Spinosad (0.5ml) was found most effective in annihilation of males of both species while the treatment without bait annihilated minimum numbers of flies. The results also suggested that more number of flies of both species were annihilated in first year of experimentation than second year.enCucurbitsBactroceraBiologyManagementThesis